30 November 1998
c. DDC system procurement
(1) Procurement. Procurement methods which have been used include:
(a) Write a five year requirements contract for DDC system components where the
requirements contract is executed as a competitive procurement. Subsequent work done by controls
contractors is then accomplished using government furnished DDC components. The contractor is
responsible for providing all non-proprietary system components (valves, actuators, sensors, wiring,
etc.), installing the government furnished proprietary components, and commissioning the entire control
system. The disadvantage to this approach is that you may encounter compatibility problems after the 5
year contract expires as there is no guarantee that the same vendor will win the next contract.
(b) Write contract for SLDC, but indicate in the contract that in lieu of SLDC the contractor
can provide DDC, but the DDC system must be compatible with the base-wide (UMCS or EMCS)
system. This approach requires two designs and two specifications (one for the SLDC system and one
for the DDC system). They will closely resemble each other, thus they are not both being developed from
scratch. The separate designs must include all drawings and complete contract specifications. The
selection of which system to use is up to the contractor. Using this approach, experience indicates that
70 to 80% of the time,or more, the contractor will provide the DDC system.
(c) Contract documents depict a non-proprietary DDC system, allowing for open competition.
This approach is best used in single-building DDC applications where the control system is strictly "local"
with no immediate or future need to interface with a supervisory system, and the facility has a dedicated
maintenance staff, such as a hospital. This use of this approach is not recommended for multiple
contracts or on a continuing basis because there is a high potential for eventually having a number of
systems provided by different manufacturers. This leads to separate systems which have unique
maintenance and training requirements, operating software, and generally will not communicate with
each other without the addition of gateway interpreters.
(d) Sole source procurement of a single vendor's DDC system. The use of this approach is
strongly discouraged due to the potential for protests which would delay contract award. A strong sole
source acquisition justification and approval would be required on each project. If protested, it is
questionable if the sole source acquisition justification could be substantiated since nonproprietary
alternatives are available which surpass the minimum needs of the Army. The resolution of protests
currently being argued may provide some insight for the use of this approach in the future; however, until
that time, it is recommended that this approach be avoided.
8. CONTROL SYSTEM STANDARDS.
loop controller signals will be standard instrumentation signals of 4 to 20 milliamperes, which can be
readily interfaced with any Corps standard EMCS, UMCS, or FM system and virtually any other central
or head end system. When required, the controller output signal will be converted to 21 to 103 kPa (3 to
b. Actuators. Actuation of valves and dampers for HVAC systems such as air handling units and
convertors will normally be by pneumatic actuators. These instructions also provide guidance on
substituting electric or electronic actuators for pneumatic actuators.